Method of making air bearing with corner steps

ABSTRACT

An air bearing slider for a disc drive includes an air bearing surface defined on the disc opposing face at least in part by a first step or cavity. An additional corner step is defined in bar processing, deeper than the first cavity. With the corner step, the first cavity does not extend quite all the way to the corner of the slider. The corner of the slider, formed on one face by dicing of the bar into individual sliders, is at an additional depth due to the corner step. The corner steps are preferably narrow, such as nominally one to two times the tolerance value on the dice cut. If a shock event occurs which causes the air bearing slider to contact the disc at certain roll and pitch angles, the corner step edge will contact the disc rather than the dice cut corner. The corner step thus lessens the probability of contact between the disc and the corners of the air bearing slider, and contact with a dice cut edge of the slider is avoided. This reduces the amount of damage to the disc drive caused by the shock event.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of provisional application No.60/059,796 filed on Sep. 22, 1997, entitled MILLED DICE CUT EDGES FORIMPROVED HEAD/DISC SHOCK ROBUSTNESS.

BACKGROUND OF THE INVENTION

The present invention relates to air bearing sliders for disc drives,and more particularly, to air bearing sliders having an air bearingsurface which is removed from a corner of the slider body.

Air bearing sliders have been extensively used in magnetic disc drivesto appropriately position a transducer above a rotating magnetic disc.The rotation of the disc at high speed generates a “wind” of airimmediately adjacent the flat surface of the disc. A disc opposing facethe air bearing slider interacts with the wind to bias the slider awayfrom the disc and against a load beam, causing the slider to “fly” asmall distance above the disc. Each slider is typically mounted on agimble or load beam assembly which biases the slider toward the rotatingdisc, providing a spring force opposite to the bearing force of the windincident on the disc opposing face of the slider.

When a disc drive is subjected to a mechanical shock of sufficientamplitude, the slider may overcome the biasing force of the load beamand lift off from the disc. Damage to the disc may occur when the sliderreturns to the disc and impacts the disc under the biasing force of theload beam. The damage to the disc can result in lost or inaccurate data,or in a fatal disc “crash” rendering the disc drive inoperable.

The contour of the disc opposing face of an air bearing slider has asignificant effect on the flying characteristics of the air bearingslider, and various contours have been proposed and used for air bearingsliders. Examples of two of these are included in U.S. Pat. No.5,062,017 to Strom et al. and U.S. Pat. No. 5,343,343 to Chapin,assigned to the assignee of the present invention and both incorporatedherein by reference.

The disc opposing face of most air bearing sliders includes a defined“air bearing surface” which is a flat surface closest to the disc orextending furthest from the body of the slider. The air bearing surfaceis generally planar, but may have a slight crown. A tapered or steppedfront edge may be included at the leading edge of the air bearingsurface. One or more cavities is defined in the disc opposing face andhaving a generally constant depth from the air bearing surface. Inparticular, many sliders include an air bearing surface made up of twoor more “rails” or “skis” running longitudinally along the disc opposingface. A large central cavity is commonly defined between two air bearingrails of the slider. In “negative pressure” air bearing sliders (orNPABs), a cross bar or other structure toward the leading edge of theslider is used to provide a negative pressure region in the centralcavity.

In some air bearing sliders, such as that shown in Strom et al., the airbearing surface may extend the full length of the slider body and mayinclude leading and trailing corners of the slider body. In other airbearing sliders, such as that shown in Chapin, a longitudinal edge stepmay be used such that the air bearing surfaces are removed inward fromcorners of the slider body.

The fabricating processes used to manufacture air bearing sliderscommonly includes photolithographic material removal processes. Inphotolithographic removal, a protective coating may be applied to aportion of the disc opposing face of the slider body, and a thin layerof material not protected by the coating may be removed by a chemical orphysical process. The chemical or physical process removes material overthe exposed surfaces at a substantially uniform rate. The depth of theremoved material is determined by the length of application time for thechemical or physical material removal process. Other processing stepsinclude mechanical removal of material such as through lapping orpolishing surfaces.

It is common to simultaneously manufacture a number of sliders arrangedside by side along a “bar”. After each of the air bearing surfaces hasbeen defined and commonly machined on the bar to the extent possible,the bar is diced into individual air bearing sliders. Because processingsteps require approximately equal expense regardless of whetherperformed on multiple aligned sliders at once or on a single slider,“bar level processing”, i.e., the simultaneous processing of multiplesliders each part of the bar and prior to dicing, is significantly moreefficient than “slider level processing”.

In bar level processing, the air bearing surface, the leading edge andthe trailing edge can be polished very flat and smooth. The surfacesproduced by the machined dice cuts, however, are quite rough with jaggededges compared to the polished edges of the air bearing surface. Becausepolishing of the side edges of the slider body would require sliderlevel processing, the sides of the slider may be left with the as cutedges and without any lapping, polishing or other finishing operationson the sides of the slider.

The disc drive industry generally desires to manufacture disc driveswhich are more robust at withstanding shock events. At the same time,the contour of the air bearing surface of sliders is dictated tomaximize flying performance, and the processing of sliders should beperformed as efficiently as possible to reduce cost. The presentinvention addresses these concerns, and provides a more robust discdrive without significantly increasing cost or sacrificing sliderperformance.

BRIEF SUMMARY OF THE INVENTION

An air bearing slider for a disc drive includes an air bearing surfacedefined on the disc opposing face at least in part by a first step orcavity. An additional corner step is defined, deeper than the firstcavity. With the corner step, the first cavity does not extend quite allthe way to the corner edge of the slider defined in the dice cut. If ashock event occurs which causes the air bearing slider to contact thedisc at certain roll and pitch angles, the edge of the first cavity wincontact the disc rather than the dice cut corner. The corner step thuslessens the damage likelihood for contact between the disc and thecorners of the air bearing slider, because contact with a dice cut edgeof the slider is avoided. This reduces the likelihood of damage to thedisc drive caused by the shock event.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a slider according to the presentinvention.

FIG. 2 is a rear view of the slider of FIG. 1.

FIG. 3 is a cross sectional view of the slider of FIGS. 1 and 2 takenalong line 3—3.

FIG. 4 shows a portion of a slider bar showing the cavity portions to bephotolithographically removed in a first processing step toward creatingthe slider of FIG. 1.

FIG. 5 shows application of a second photolithographic material removalstep to the slider bar of FIG. 4 toward creating the slider of FIG. 1.

FIG. 6 shows application of a third photolithographic material removalstep to the slider bar of FIG. 5 toward creating the slider of FIG. 1.

FIG. 7 shows the slider bar of FIG. 6 after dice cutting.

FIG. 8 is a plan view of an alternative embodiment of a slider of thepresent invention.

FIG. 9 is a perspective view of a second alternative embodiment of aslider of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-3 show a first embodiment of an air bearing slider 10 accordingto the present invention. Depth has been significantly exaggerated inFIGS. 1-3 to show detail The air bearing slider 10 includes a sliderbody 12 with a disc opposing face 14 bounded by a leading face 16, atrailing face 18, and side faces 20 running from the leading face 16 tothe trailing face 18. The leading face 16 and the trailing face 18 arepreferably polished smooth, while the side faces 20 may be relativelyrough. When used in the disc drive, the disc opposing face 14 isdirected toward the disc. Generally speaking, the contours of the discopposing face 14 determine the flying characteristics entirely, and theshape of the remainder of the slider body 12 is not critical.

The disc opposing face 14 intersects the leading face 16 at a leadingedge 22, intersects the trailing face 18 at a trailing edge 24, andintersects the side faces 20 at side edges 26. The side edges 26intersect the leading edge 22 at leading corners 28 and intersect thetrailing edge 24 at trailing corners 30. A longitudinal axis 32 can bedefined for the disc opposing face 14 spaced central to the side edges26.

The disc opposing face 14 has an air bearing surface 34 which in thisembodiment is made up of two longitudinally extending rails 36 and acenter rail or trailing central pad 38. The rails 36 do not extend forthe full length of the slider 10, but rather are removed from thetrailing edge 24. The trailing central pad 38 extends to the trailingedge 24, but is removed or spaced significantly inward from the trailingcorners 30.

The air bearing surface 34 interacts with the wind incident thereon tocause the slider 10 to “fly” above a moving disc. To ensure consistentinteraction between the air bearing surface 34 and the wind, the airbearing surface 34 is a relatively smooth surface. The shape anddimensions of the air bearing surface 34 may be selected as necessary toachieve the desired flying characteristics. For instance, the slider 10may have a preferred width of 1000 microns, and the trailing central pad38 may be 250 microns wide. A transducer 40 such as a read/write thinfilm head may be carried on the trailing edge 24 of the slider 10, toread information from and write information to the disc. The transducer40 may cover only a small area on the trailing face 18 as shown, or mayalternatively cover the entirety of the trailing face 18, and may befabricated in any shape, size and method as known in the art.

During operation of the disc drive, the slider 10 generally flies at apositive pitch angle, with the trailing edge 24 of the slider 10 (andthe transducer 40 thereon) closest to the disc. The pitch angle maychange somewhat based on the local wind velocity, primarily determinedby the radial location of the slider 10, but the air bearing surface 34is generally intended to minimize variances in pitch angle. Duringoperation of the disc drive, the slider 10 may be accessed across thedisc by a rotary actuator (not shown) so as to encounter a variety ofskew angles relative to the wind. The slider 10 may exhibit variouspositive and negative roll angles about the longitudinal axis 32 atdifferent skew angles and different access rates, but is generallyintended to minimize roll. As shown, the air bearing surface 34 may havea relatively complex shape and geometry to provide the desired flyingcharacteristics for the slider 10. When the disc drive stops operating,the slider 10 is positioned at a landing zone and the disc slowed to astop, during which time the slider 10 will contact the disc and park onthe disc. In the parked position, the air bearing surface 34 will form agenerally flat contact against the surface of the disc so the slider 10is parked with zero pitch angle and zero roll.

A leading step 42 is provided along the leading edge 22 of the slider10, such as extending for about 20% of the slider length. The leadingstep 42 is fairly shallow, but nonetheless can be considered as a cavityremoved from the air bearing surface 34. For instance, the leading step42 may have a depth of about 0.3 microns relative to the air bearingsurface 34. A portion of the leading step 42 adjacent the rails 36 helpsto pressurize air onto the rails 36 during flying. Alternative to theleading step 42, a leading edge taper may be provided along the leadingedge 22 of the air bearing surface 34.

A central portion 44 of the leading step 42 serves as a cross rail.Alternative to this central portion 44, a cross-rail structure may beprovided separate and distinct from the leading step 42 or any leadingedge taper.

A main cavity 46 is located behind the leading step 42, such asextending for about the trailing 80% of the slider length. With thecentral portion of the leading step 42 contacting the wind before themain cavity 46, the main cavity 46 has a slightly negative pressureduring flying. The magnitude of the negative pressure increases withincreased wind velocity (at outer tracks on the disc), to offset theincreased positive pressure on the air bearing surface 34 caused by theincreased wind velocity, such that the slider 10 maintains asubstantially uniform fly height at all data tracks on the disc.Alternatively, the slider 10 may be designed such that the main cavity46 has a slightly positive or ambient pressure. In either event, thepressure on the main cavity 46 during flying will be significantly lessthan the pressure on the air bearing surface 34.

The main cavity 46 has a substantially flat base 48, and sides 50 whichare generally perpendicular to the cavity base 48. The cavity base 48 issubstantially parallel to the air bearing surface 34, so all of the maincavity 46 has a generally constant depth. The main cavity 46 may be asdeep as needed for the desired flying characteristics of the slider 10,such as a depth about 3 to 5 microns relative to the air bearing surface34. The cavity base 48 and the cavity sides 50 are fairly smooth. Thegenerally constant depth cavity 46 to a flat cavity base 48 is resultantfrom standard fabrication techniques, but is not overly critical toflying performance. Depending on the specific fabrication techniquesused, the cavity base 48 may be slightly sloped, rougher or more roundedwithout significantly affecting flying characteristics of the slider 10.

The location of the cavity sides 50 defines the shape of the air bearingsurface 34, and the air bearing surface 34 has a peripheral edge 52where the air bearing surface 34 meets the cavity sides 50. The airbearing surface 34 is slightly removed from the side faces 20 of theslider body 12, such that the cavity base 48 continues to extend aroundthe rails 36 of the air bearing surface 34 and form a side step 54.Because both the air bearing surface 34 and the cavity sides 50 aresmooth, the peripheral edge 52 of the air bearing surface 34 is arelatively smooth edge.

A corner step 56 is provided at each of the trailing corners 30 of theslider 10. The preferred corner step 56 extends for only a portion ofthe length of the slider body 12, that is, for only the length that therails 36 are removed from the trailing face 18. The corner step 56 has asubstantially flat base 58, and sides 60 which are generallyperpendicular to the corner step base 58. The corner step base 58 issubstantially parallel to the air bearing surface 34, so all of thecorner step 56 has a generally constant depth. The corner step 56 has adepth which is greater than the depth of the adjacent main cavity 46,such as a depth of about 7 microns. The corner step base 58 and thecorner step sides 60 are fairly smooth. Particularly when on thetrailing corners 30 of the air bearing slider 10 and when separated fromthe air bearing surface 34, the depth and surfaces of the corner step 56are not overly critical to flying performance. Depending on the specificfabrication techniques used, the corner step 56 may have slightlysloped, rougher or more rounded surfaces without significantly affectingflying characteristics of the slider 10.

The sides 60 of the corner step 56 intersect the main cavity base 48 ata corner step edge 62. Because both the main cavity base 48 and thecorner step sides 60 are smooth, the corner step edge 62 is a relativelysmooth edge.

FIGS. 4-7 show a portion of bar 64 for processing into multiple sliders10 such as shown in FIGS. 1-3. The cross-hatched portion of FIG. 4reflects a first photolithographic material removal to form the maincavity 46. The oppositely hatched portion of FIG. 5 reflects a secondphotolithographic material removal to form the leading step 42. Thethird hatched portion of FIG. 6 reflects a third photolithographicmaterial removal to form corner steps 56. The material removal stepsshown in FIGS. 4-6 can be performed in any order, but at least threesteps are generally necessary to define three different depths from theair bearing surface 34. However, if the leading step 42 has the samedepth from the air bearing surface 34 as the depth of the corner steps56 from the main cavity 46, then the second and third photolithographicmaterial removal steps can be combined such that only two steps arerequired.

The main cavity 46, the leading step 42 or the corner steps 56 may beformed such as by either ion milling or reactive ion etching. Otherprocesses can also be used as known in the art of material removal, andthe term “photolithographic removal”, as used herein, refers to anyprocess used to remove material from specific defined areas on theslider bar 64. The several photolithographic removal steps used inprocessing the sliders 10 of the bar 64 define the air bearing surfaces34. The photolithographic removal steps results in cavity sides 50,cavity bases 48, and corner step sides 60 which are relatively smooth.

The portion of the bar 64 shown includes three full locations forsliders 10. The bar 64 can extend as long as desired and include as manylocations for sliders 10 as desired for efficient bar level processing.

The air bearing surfaces 34 are typically finished in bar levelprocessing with a polishing or lapping operation. The finishing of theair bearing surfaces 34 can be performed either before, after or inbetween the photolithographic removal processes. In either event, theperipheral edges 52 of the air bearing surface 34, created with afinishing operation on the air bearing surface 34 and aphotolithographic removal process on the cavity sides 50, are relativelysmooth edges.

The bar 64 includes the leading face 16 and the trailing face 18 foreach of the sliders 10. Each of the leading face 16 and the trailingface 18 may be lapped or polished in bar level processing, or before thebar 64 is cut from the wafer, to provide the proper leading and trailingedge 22, 24 of the slider 10. The finishing of the leading face 16 andtrailing face 18 can be performed either before or after the finishingof the air bearing surfaces 34, and either before, after or in betweenthe photolithographic removal processes.

Preferably after the photolithographic removal processes and after thefinishing operations, the bar 64 is dice cut in the locations shown inFIG. 7 into individual sliders 10. Each of the dice cuts may beperformed such as with a diamond wheel saw. The dice cut results inrelatively rough side faces 20 for each of the sliders 10. The locationof the dice cut relative to the photolithographically defined airbearing surfaces 34 is subject to a tolerance, such as about plus orminus 25 microns.

A primary benefit of air bearing sliders 10 according to the presentinvention is in reducing the amount of damage to the disc drive causedby a shock event. In particular, the air bearing slider 10 of thepresent invention has a lessened probability of contact between eitherof the trailing corners 30 and the disc during a shock event.

Experimental evidence of shock events in prior art devices indicatesthat when the initial contact or recontact of the slider to the discoccurs at one of the dice cut corners, the damage to the disc is worsethan when the initial contact point is a milled air bearing corner.Presumably this is because of the more jagged or rough nature of thedice cut surfaces, as compared to the smoother peripheral edges of theair bearing surface 34 formed at an intersection between a finishedsurface and a photolithographic removal surface.

Side faces 20 of the slider 10 could be made smoother by polishing theside faces 20 after cutting. However, in part because the polishingoperation would have to be performed individually on each slider 10,i.e, in slider level processing rather than in bar level processing,this would be a difficult and uneconomical operation.

It is not necessary to polish the side faces 20 of the slider 10 of thepresent invention to mitigate the shock damage. Rather, the corner steps56 of the present invention remove the dice cut corners 30 beyond thecavity depth so as to preclude contact between the trailing corners 30and the disc at certain pitch and roll angles. The preferred corner step56 protects against contact between the trailing corners 30 and the discat roll angles of about 1° or more, and more preferably at roll anglesof about 3° or more, and most preferably at roll angles of 5° or more.

To explain how the corner steps 56 of the present invention lessen theprobability of contact between a disc and the trailing corners uponshock, consider the geometry of the preferred embodiment described withreference to FIGS. 1-7, but not having the corner steps 56. With atrailing central pad 38 width of 250 microns centered in a slider 10 of1,000 microns width, the main cavity base 48 extends for 375 microns oneach side of the trailing central pad 38. That is, the trailing portionof the air bearing surface 34 is removed laterally inward from thetrailing corner by a distance of 375 microns. With a main cavity depthof 3 microns, and assuming a pitch large enough that the rails 36 arehigher than the trailing corner, a roll angle of arctan (cavitydepth/laterally removed distance)=arctan(3/375)=0.46° or more results inthe trailing corner contacting the disc. The present invention isparticularly intended for modification of such slider designs where thetrailing corner 30 would contact at a roll angle of 1° or less.

In contrast, considering again the slider 10 of the present inventionwith corner steps 56 having a corner step depth of 7 microns, thetrailing corner 30 will not contact the disc unless the roll angle is atleast arctan (7/375)=1.07°. With a corner step depth of 10 microns, thetrailing corner 30 will not contact the disc unless the roll angle is atleast arctan (10/375)=1.53°. At roll angles less than these values,contact is with the trailing pad 38 of the air bearing surface 34, whichwill generally not cause catastrophic damage.

At roll angles greater than 1.07°, whether the trailing corner 30contacts the disc depends on the width of the corner step 56 along thetrailing edge 24 of the slider 10. If the corner step 56 is sufficientlynarrow, the corner step edge 62 will contact the disc rather than thetrailing corner 30. For example, if the corner step 56 is 4 microns wideand 4 microns deeper than the main cavity 46, the corner step 56 willprevent contact between the trailing corner 30 and the disc up to a rollangle or arctan (4/4)=45°. Thus a very narrow corner step 56 willprevent contact between the trailing corner 30 and the disc up to a highroll angle.

However, the corner step width cannot be selected tighter than thetolerance on the dicing location, which is further discussed withreference to FIG. 8. FIG. 8 shows a slider 70 with corner steps 72 of analternative shape. The corner steps 72 have a corner step edge 74 whichis generally parallel to the respective side edge 26 and the trailingedge 24, making each corner step 72 as narrow as possible. Because thecorner steps 72 are very narrow, contact with the trailing corner 30 andthe disc will be prevented at a high roll angle.

Additionally, FIG. 8 shows the effect of the tolerance on the dicinglocation. As shown in FIG. 8, the dice cuts may be offset relative tothe longitudinal axis 32 of the air bearing surface 34 by an amount upto the tolerance value. The offset due to the tolerance of the dice cutsis most easily seen with reference to the edge steps 54, shown in FIG. 8with edge step 54 a significantly wider than edge step 54 b. Forinstance, if the tolerance of the dice cuts is plus or minus 25 microns,edge step 54 a may be up to 50 microns wider than edge step 54 b.

With a tolerance on the dicing location at about plus or minus 25microns, a nominal corner step width of 4 microns would translate to anactual corner step width anywhere from 0 (ie., not present) to 29microns. The possibility of having a corner step 72 removed due to thetolerance on the dice cut operation should be avoided.

Accordingly, the size of the corner step 56 prior to dice cutting shouldextend inward on each air bearing slider 10 at least to most inwardtoleranced dice cut location. For instance, if the tolerance on the dicecut is plus or minus 25 microns, the corner step 56 should be at leastnominally 25 microns. If the corner step 56 is nominally 25 microns, anactual corner step 56 will be from 0 to 50 microns wide. Assuming thecorner step 56 is 4 microns deeper than the main cavity 46, a cornerstep 56 of just over 0 microns actual width will prevent contact betweenthe trailing dice cut corner 30 and the disc up to a roll angle orarctan (4/0)=90°. A corner step 56 of 50 microns actual width willprevent contact between the trailing corner 30 and the disc up to a rollangle or arctan (4/50)=4.58°.

More preferably, the corner steps 72 are nominally sized to extendinward beyond a most inward toleranced dice cut location by a smallamount, such as the amount of the tolerance value or less. That is, witha tolerance on the dice cut of plus or minus 25 microns, the corner step72 should be nominally one to two times the tolerance value, ornominally 25 to 50 microns wide. If the corner step 72 is nominally 50microns wide, an actual corner step 56 will be from 25 to 75 micronswide. To ensure that dice cut corner contact is prevented up to a rollangle of 5°, the corner step 72 of 50 micron nominal width should be75*tan(5°)=6.6 microns deeper than the main cavity 46, such as a cornerstep depth of 10 microns with a cavity depth of 3 microns. At rollangles between arctan(7/75)=5.30 and arctan(3/325)=0.53° and a highpitch angle, contact is with the corner step edge 72, which willgenerally not cause catastrophic damage. At roll angles less thanarctan(3/325)=0.53°, contact is with the trailing pad 38 of the airbearing surface 34, which will generally not cause catastrophic damage,

The term “contact”, as used thus far, refers to the initial contactbetween the slider 10 and the disc assuming no deformation. However,neither the disc nor the slider 10 is entirely rigid. Instead, both canundergo some degree of temporary deformation prior to any permanentdeformation. Damage to the disc drive most often occurs as permanentdeformation of the disc caused by the impact between the slider 10 andthe disc during a shock event. Due to temporary and/or permanentdeformation of the disc and/or slider 10, actual contact occurs over alarger surface than the initial point contact considered thus far.

The corner step edge 74 of the embodiment of FIG. 8 is parallel to thelongitudinal axis 32 of the slider 70 and relative to the side edge 26.The corner step edge 62 of the embodiment of FIGS. 1-7 is at an anglerelative to the longitudinal axis 32 of the slider 10 and relative tothe side edge 26. Depending upon the position of the corner step edge62, 74 and the attitude of the slider 10 upon contact, angling of thecorner step edge 62, 74 may further limit the amount of damage. Inparticular, contact damage and permanent deformation is more pronouncedif the edges of a corner are all at a high angle to the plane of thedisc upon contact. If contact is more spread toward a line or a surfaceof contact rather than at a direct point, more of the impact force willbe withstood through temporary deformation over a larger area and lessthrough permanent deformation at a point. Contact of the corner stepedge 62 can only occur when both significant pitch and significant rollare present. Angling the corner step edge 62, 74 can help for contact tobe spread more along the length of the corner step edge 62, 74 ratherthan at a specific point. Angling of the corner step edge can thus beused to further minimize damage upon contact.

If the pitch is not large, it will not be necessary to mill as deep toprevent contact between the corners 30 and the disc. Through carefuldesign of suspension assemblies, some progress has been made incontrolling the contact attitude of the slider 10 so the slider 10recontacts the disc with a controlled, near-zero static attitude.Despite improved suspension design, it is not always possible to causethe slider 10 to contact on the air bearing surface 34. For a particulardesign, if the limits on both the pitch and roll at contact are known,then the design of the slider 10 may include a shallower corner step 56,72 to ensure that contact on the dice cut corner 30 is prevented.

Thus far we have only discussed placing corner steps 56, 72 at trailingcorners 30. Because the sliders 10, 70 flies at positive pitch angles,normally the leading corners 28 will not make first contact with thedisc at a shock event. However, some shock events may cause the slider10, 70 to impact the disc at a negative pitch angle, such as shockevents that occur while the disc drive is not operating. FIG. 9 shows analternative slider 80 of the present invention which helps to preventdamage in such situations. The slider has a corner step 82 at leadingcorners 28. The corner step 82 at leading corners 28 functions the sameway as the corner steps 56, 72 at trailing corners 30, but is effectivefor contact at negative pitch angles as opposed to positive pitchangles.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A method for manufacturing a plurality of airbearing sliders for a disc drive from a bar having a substantially flatface, comprising: recessing a cavity surface having a substantiallyuniform cavity depth into the bar, non-recessed portions defining airbearing surfaces of a plurality of air bearing sliders; recessing cornerareas having a substantially uniform step depth into the bar, thesubstantially uniform step depth being greater than the substantiallyuniform cavity depth; and dicing the bar into a plurality of air bearingsliders, whereby at least portions of the recessed corner areas becomecorners of each of the air bearing sliders.
 2. The method of claim 1,wherein the act of recessing a cavity surface comprises recessing withphotolithography, wherein the act of recessing corner areas comprisesrecessing with photolithography, and wherein the substantially uniformcavity depth and the substantially uniform step depth are both measuredrelative to the air bearing surfaces of the plurality of air bearingsliders.
 3. The method of claim 1, wherein the act of dicing comprisingdicing dice cuts located on the bar with a tolerance value, wherein theact of recessing corner areas comprises recessing corner areas which arenominally sized to extend inward on each air bearing slider from one totwo times the tolerance value.
 4. The method of claim 3, wherein the actof recessing corner areas comprises recessing corner areas which arenominally sized to extend inward on each air bearing slider to the mostinward toleranced dice cut location.
 5. The method of claim 1, whereinthe act of recessing corner areas comprises recessing corner areas bothat leading corners and trailing corners of the air bearing slider. 6.The method of claim 1, further comprising: recessing a second cavityinto the bar, the second cavity having a substantially flat secondcavity surface substantially parallel to the air bearing surfaces at asecond cavity depth from the air bearing surfaces different from thesubstantially uniform cavity depth, wherein the substantially uniformstep depth of the corner areas is greater than the second cavity depth.7. The method of claim 1, wherein the act of dicing defines a side edgeof the slider body which does not intersect the air bearing surface. 8.The method of claim 1, wherein the substantially flat face of the barextends between a first edge and a second edge, wherein the act ofrecessing a cavity surface recesses the cavity surface into thesubstantially flat face of the bar; wherein the act of recessing cornerareas recesses corner areas which are substantially parallel to the airbearing surfaces, the corner areas intersecting at least one of thefirst edge and the second edge of the bar; and wherein the act of dicingthe bar creates dice cuts intersecting at least portions of the recessedcorner areas to form at least one leading or trailing corner of each ofthe air bearing sliders at the substantially uniform step depth.
 9. Themethod of claim 8, wherein the act of recessing corner areas comprisesrecessing corner areas both at the leading corners and the trailingcorners of the air bearing slider.
 10. The method of claim 8, whereinthe act of recessing corner areas defines an edge which is neitherperpendicular nor parallel to the first edge and the second edge of thebar.
 11. The method of claim 8, further comprising: recessing a firststep into the substantially flat face of the bar as part of the airbearing surface at a first step depth less than the cavity depth suchthat the first step will interact with incident wind on the air bearingslider with a positive pressure, the first step separating the airbearing surface from the recessed corner area.
 12. The method of claim1, wherein the dicing act creates a plurality of air bearing sliderseach comprising: a slider body having a disc opposing face comprising: aleading edge; a trailing edge opposite the leading edge and defining alength of the slider body; side edges substantially defined by thedicing running from the leading edge to the trailing edge, each sideedge intersecting the leading edge at a leading corner, each side edgeintersecting the trailing edge at a trailing corner, with the airbearing surface being disposed inward from at least one of the leadingcorners and trailing corners; and a corner step, the corner step havinga substantially flat corner step surface substantially parallel to theair bearing surface at a corner step depth from the air bearing surface,the corner step including said at least one of the leading corners andtrailing corners, wherein the corner step depth is greater than thecavity depth.
 13. The method of claim 12, wherein the acts of recessingcorner areas and dicing define a corner step which extends for only aportion of the length of the slider body.
 14. The method of claim 12,wherein the acts of recessing corner areas and dicing define a cornerstep is sufficiently narrow to prevent contact between said at least oneof the leading corners and trailing corner and a planar surface of adisc, at least at some combinations of pitch and roll of the air bearingslider relative to the planar surface of the disc.
 15. The method ofclaim 14 wherein the acts of recessing corner areas and dicing define acorner step at the trailing corner, and wherein the corner step preventscontact between the trailing corner and the planar surface at a roll of1° and at a high pitch angle.
 16. The method of claim 15 wherein theacts of recessing corner areas and dicing define a corner step whichprevents contact between the trailing corner and the planar surface at aroll of 3° and at a high pitch angle.
 17. The method of claim 12 whereinthe acts of recessing corner areas and dicing define a corner step whichprevents contact between the trailing corner and the planar surface at aroll of 5° and at a high pitch angle.
 18. The method of claim 12,further comprising: recessing a portion of the substantially flat faceof the bar such that the air bearing surface has a trailing portionremoved laterally inward from the side edge by a laterally removeddistance measured parallel to the trailing edge, wherein arctan(cavitydepth/laterally removed distance)<1°.
 19. A method for manufacturing aplurality of air bearing sliders for a disc drive from a bar having asubstantially flat face extending between a first edge and a secondedge, comprising: recessing a cavity surface having a substantiallyuniform cavity depth into the substantially flat face of the bar,non-recessed portions defining air bearing surfaces of a plurality ofair bearing sliders; recessing corner areas having a substantiallyuniform step depth into the bar, the corner areas being substantiallyparallel to the air bearing surfaces, the corner areas intersecting atleast one of the first edge and the second edge of the bar, thesubstantially uniform step depth being greater than the substantiallyuniform cavity depth; and dicing the bar into a plurality of air bearingsliders, wherein the dice cut intersects at least portions of therecessed corner areas to form at least one leading or trailing corner ofeach of the air bearing sliders at the substantially uniform step depth.20. A method for manufacturing a plurality of air bearing sliders for adisc drive from a bar having a substantially flat face, comprising:recessing a cavity surface having a substantially uniform cavity depthinto the bar, non-recessed portions defining air bearing surfaces of aplurality of air bearing sliders; recessing corner areas having asubstantially uniform step depth into the bar, the substantially uniformstep depth being greater than the substantially uniform cavity depth;and dicing the bar into a plurality of air bearing sliders, each airbearing slider comprising: a slider body having a disc opposing facecomprising: a leading edge; a trailing edge opposite the leading edgeand defining a length of the slider body; side edges substantiallydefined by the dicing running from the leading edge to the trailingedge, each side edge intersecting the leading edge at a leading corner,each side edge intersecting the trailing edge at a trailing corner, withthe air bearing surface being disposed inward from at least one of theleading corners and trailing corners; and a corner step, the corner stephaving a substantially flat corner step surface substantially parallelto the air bearing surface at a corner step depth from the air bearingsurface, the corner step including said at least one of the leadingcorners and trailing corners, wherein the corner step depth is greaterthan the cavity depth.